Rheumatic fever

Question 1

What is rheumatic fever?

Answer 1

Develops following an immunological reaction to recent (2-6 weeks ago) Streptococcus pyogenes infection.

Question 2

What is the pathogenesis of rheumatic fever?

Answer 2

1. Activation of the innate immune system
2. B and T cells = IgG and IgM antibodies and CD4+ T cells are activated
3. Cross-reactive immune response (type II hypersensitivity)

• molecular mimicry
• M protein in cell wall
• antibodies against M protein cross-react with myosin and the smooth muscle of arteries

4. Aschoff bodies = the granulomatous nodules

Question 3

How do you diagnose rheumatic fever?

Answer 3

Diagnosis is based on evidence of recent streptococcal infection accompanied by:

• 2 major criteria
• 1 major with 2 minor criteria

Question 4

How do you evidence recent Strep infection?

Answer 4

Evidence of recent streptococcal infection

• raised or rising streptococci antibodies,
• positive throat swab
• positive rapid group A streptococcal antigen test

Question 5

What are major criteria?

Answer 5

• erythema marginatum
• Sydenham’s chorea: this is often a late feature
• polyarthritis
• carditis and valvulitis (eg, pancarditis)*
• subcutaneous nodules

Question 6

What are minor criteria?

Answer 6

• raised ESR or CRP
• pyrexia
• arthralgia (not if arthritis a major criteria)
• prolonged PR interval